Inflatable packer formation tester with separate production pockets



July 15, 1958 R. H. BLOOD 2,843,208

INFLATABLE FACKER FORMATION TESTER WITH SEPARATE PRODUCTION POCKETS Filed Jan. 22, 1954 4 Sheets-Sheet 1 l0 I :2: z 4

=2 L4: 23 11:? zs- A 1 II Inventor Robert H. Blood Attorney R. H. BLOOD 2,843,208 INFLATABLE PACKER FORMATION TESTER WITH SEPARATE PRODUCTION POCKETS July 15, 1958 Filed Jan. 22, 1954 4 Sheets-Sheet 2 Inventor Robert H. Blood Attorney 444 y 95& R. H. BLOOD 2,843,208

INFLATABLE PACKER FORMATION TESTER WITH SEPARATE PRODUCTION POCKETS' Filed Jan. 22. 1954 4 Sheets-Sheet 3 Robert H. Blood July 15, 1958 R BLOOD 2,843,208

INFLATABLE PACKER FORMATION TESTER WITH SEPARATE PRODUCTION POCKETS Filed Jan. 22, 1954 4 Sheets-Sheet 4 Inventor Robert H. Blood Attorney jaw,

asssnss llf lFLA'll'AlBLE FAQKER FGRMATION TESTER SEPARATE PRQYEUCTION PUCKET Robert H. Eiocd, Tulsa, him, assignor to Esso Research and Engineering Cornpany, a corporation of Delaware Application January 22, 1954, Serial No. 465,587

3 @lairns. (tCl. 166-400) This invention relates to an improvement in apparatus for testing a bore hole in the earth to determine the nature of fluids produced from various subsurface strata encountered by the bore hole. More particularly, the invention concerns an improved formation tester of the inflatable packer type wherein provision is made for fluid production from an increased area of the bore hole wall.

in conventional oil well drilling operations, fluids known as drilling muds are employed to aid in carrying away cuttings and also to maintain a hydrostatic head in the Well to prevent the uncontrolled escape of gases or fluids from various formations encountered during drilling. One disadvantage of drillingwith a drilling mud is that the sampling of natural fluids occurring in various formations is thereby rendered difiicult. To overcome this disadvantage various types of formation testers have been devised which are provided with means for reducing the hydrostatic pressure in the vicinity of the forma tion to be tested in order that a sample of the natural fluids can be taken. Many of these formation tester are provided with elastic sleeves or packers for sealing off the portion of the Well in which it is desired to reduce the hydrostatic pressure. The use of such elastic packers is particularly desirable since such a packer can be expanded to give a thorough seal and yet may be readily removed from the well after being deflated. Furthermore, it is possible to position such an elastic packer at any desired point in the well with very little difliculty.

In formation testers of the type that employ inflatable elastic packers, a major portion of the surface of the packer is required for sealing off the stratum that is to be tested so as to isolate it from the remainder of the bore hole for the purpose of minimizing or preventing contamination of the sample fluids by drilling mud and for the purpose of permitting a decrease in hydrostatic pres sure over a selected area of the stratum under test in order to enable formation fluid to flow into the tester. it is thus apparent that with this type of tester a problem is encountered in that an elfective passageway for produced fluids must be provided in the same general area of the packer that is serving to seal off the formation under test from the fluids that are present in the well. Such a passageway may consist of a flexible tube extending from the sample chamber within the tester and terminating in an opening through the Wall or" the packer. An arrangement of this sort would not be very satisfactory from a practical standpoint in view of the limited area through which formation fluids could be produced.

. Furthermore, it would not be practical to provide a plurality of such tubes terminating in a plurality of openings in the packer wall so as to provide more producing area in view of the difl iculty and considerable expense that would be involved in such a tester.

One solution to the problem of providing enlarged non-collapsible testing areas in the wall of an inflatable packer of a formation tester has been to employ in the wall of the packer external recesses or pockets filled with interconnected filling material, viz. packing elements such as bead chain, so as to render the pockets non-collapsible. The filling material at the same time define interstices through which fluid may flow. Fluid communication between such pockets or recesses and a sample receiving chamber within the tester is established through collapse resistant tubes that pass through the packer wall. By utilizing interconnected filling material in this manner, it is possible to construct a relatively simple and inexpensive testing apparatus in which a larger area of the packer can be placed into contact with at producing stratum than is possible with simple packer Wall openings, for the purpose of collecting a fluid sample. A formation tester of this type is disclosed and claimed in U. S. Patent 2,600,173 of Ben W. Sewell and George H. Ramsey, issued June 10, 1952.

Although a formation tester of the type just described constitutes a decided improvement over earlier types, it still leaves much to be desired. Since the external pockets or recesses that receive the interconnected filling material are molded into the wall of the inflatable packer and are of necessity reinforced with fabric or equivalent material, they cannot stretch when the packer is inflated. Hence the portion of the packer that does not contain reinforcing fabric, and thus is available for expansion, is limited. As a result the proportion of the circumference of the bore hole that can be covered by the production pockets, and hence the area of the stratum that is under test that can be exposed to the Zone of re duced pressure for the production of fluid into the formation tester, is somewhat limited.

it is an object of the present invention to furnish a formation tester of the inflatable packer type in which a maximum area of the producing formation can be placed into contact with the fluid receiving ports of the tester without limiting the extent to which the inflatable packer can be expanded to till the section of the bore hole under test so as to isolate the fluid producing stratum.

In accordance with the present invention, a formation tester is provided that has an inflatable packer in which no fabric or other reinforcing agents are employed around the entire circumference of the packer in the region of the production pockets. Instead these pockets are positioned in one or more separate fabric-reinforced memhers, i. e. pocket strips, that are supported entirely outside of the fluid envelope or packer. The pockets are so designed that when the packer is in the deflated condition the pockets will cover approximately the full cir cumference of the testing device. When the packer is inflated in the bore hole, it is free to expand over its full circumference, a relative motion or sliding taking place between the packer and each pocket supporting member that is mounted exterior of the packer. The advantage thereby gained is that the packer can expand to a large diameter while the tester still provides a gen erous producing area. i

The nature and objects of this invention will be more fully understood when reference is made to the accompanying drawings, in which:

Figure 1 is an elevational View, in broken section, of one embodiment of the invention in expanded position in a bore hole;

Figure 2 is a section taken on line lI-li of Figure 1 showing the manner of clamping the top of the packer element and the pocket strips to the mandrel;

Figure 3 is a section taken on line ill-4H of Figure 1 showing in a manner similar to Figure 2. the mounting of the lower end of the packer and the pocket strips.

Figure 4 is a fragmentary view of the clamping arrangement;

Figure 5 is a section taken on line V-V of Figure 1 showing the relation of the packer to the pocket strip when the packer is inflated;

Figure 6 is a section taken on line Vl-VI of Figure 1 to illustrate the extent to which the pockets cover the periphery of the bore hole;

Figure 7 is a sectional elevation of the packer in its deflated condition; and

Figure 8 is a section taken on line VIIIVH of Figure 7 showing the relation of the pockets to the packer when the packer is in the deflated position.

Referring now to particular features of the drawings, a bore hole 10 is diagrammatically illustrated traversing a subsurface stratum 20 whose fluid producing properties are to be tested. The uncased bore hole has been drilled with conventional apparatus, the drill bit has been re moved from the bore hole, and the formation testing apparatus that is illustrated in the drawing has been attached to the lower end of a drill pipe if and lowered into the bore hole so as to be adjacent stratum 2d. The testing apparatus is mounted on a mandrel 12 that has been attached to the lower end of the drill pipe. An

inflatable elastic packer 13 is attached at its upper and lower ends to the mandrel by means of clamps 15. Separately mounted on the exterior of the packer 13 are elongated outer pocket strips 14, the upper and lower ends of which are also held by clamps l5. Conveniently these clamps are of the split ring type with the clamps drawn together by means of bolts 116 as illustrated in the fragmentary view in Figure 4'. The pocket strips 14- are fabric-reinforced members that are entirely separate from the inner packer l3. Conveniently the inner packer 13 and the outer pocket strips 14 are made of molded rubber.

The pocket strips are molded so as to provide pockets 17 intermediate their ends into which are placed interconnected filling material 1.8 such as bead chain, intermeshed wire spirals, link chain, or the like, in essentially the same manner as described in the aforementioned patent of Sewell and Ramsey, thereby furnishing noncollapsible production pockets through which fluids from the tested formation may flow. The packing elements lfi'may be secured within the pockets 17 by equipping the pockets with tongues 42 to support wires 43. The wires may be passed around the packing elements and thereby hold them securely in position.

The individual strips are separate from one another as mentioned earlier in this description and as especially illustrated in Figures 2, 3, 5, 6 and 8. Each strip, furthermore, is reinforced in the vicinity of its pocket; but at least a portion of the strip which is not in the vicinity of its pocket is free of reinforcement so as to stretch readily upon expansion of packer 13. Thus, in Figures 1, 2 and 5 reinforcement is depicted as extending from the upper end of each strip 1 to a point just below the pocket 17 positioned in the strip. Conversely, the lower portion of each strip in these figures is illustrated as being free of any reinforcement so as to insure adequate stretching quality in the strip. Connecting each pocket with the interior of the drill string is a non-collapsible flexible producing tube which may conveniently be constructed in the same manner as flexible shaft housing such as is used for automobile speedometer cables and the like. As illustrated, the flexible producing tubes 11.9 may be molded into the pocket strips for protection. The upper end of mandrel 12 is provided with suitable grooves to receive the shaped portion of the pocket strip that is held by the clamps, as shown in the sectional view shown in Figure 2.

Other features of the testing apparatus are essentially the same as described in the aforementioned patent of Sewell and Ramsey. Thus the mandrel 12 is provided with an interior passageway 25 that terminates at its upper end in a port 26 exterior of the mandrel above the packer and in one or more ports 27 exterior of the mandrel below the packer so as to provide a bypass channel for well fluids between regions in the bore hole above the packer and regions below the packer. This bypass channel serves to equalize the hydrostatic pressures acting on the elastic packer so that no pressure will exist that will tend to force the packer upward or downward in the bore hole. For ease of illustration port 26 is shown as being behind the mandrel in Figure 1. Further like the apparatus in the Sewell and Ramsey patent, mandrel 12 in the present apparatus is provided at its upper end with check valves to control the flow of fluids within the inner packer 13 and within the tubes 19. Thus a suitable check valve 40 is provided in the inflation channel 23 as particularly shown in Figure 1 so as to maintain the packer in its inflated condition during a test. Also, a check valve 41 is provided at the upper end of each producing tube 19 which is operative to prevent flow of fluid in a downward direction through these tubes, but to permit flow of fluid upwardly in the tubes and into the drill string. The check valves 41 act to prevent fluid loss from the drill string through the tubes 19 when the packer is being inflated.

It is to be understood further that the testing apparatus is lowered into the bore hole with the packer in the deflated condition and that the packer is then inflated after the proper depth has been reached. With the packer inflated and with the production pockets thus placed in contact with the formation to be tested, the pressure within the drill string is reduced by suitable means until it is below the pressure existing in the formation being tested, thus permitting formation fluid to flow through the producing tubes 19 into the drill string. Conveniently the required reduction in pressure can be effected by use of a sample chamber run into the drill string on a wire line to seat in a special section of drill pipe arranged immediately above the formation tester. A suitable sample chamber assembly that can be used for this purpose is described in U. S. Patent 2,661,803 of George H. Ramsey, issued December S, 1953. After the test has been completed, the sample chamber is retrieved and the packer is deflated by releasing the check valve associated with the inflation channel.

If reference is made to Figures 7 and 8, of the drawing, which present views of the packer in its deflated condition, certain additional features of the invention will be apparent. It will be noted that, except for the cord 29 arranged longitudinally of packer 13 adjacent each end of the packer to control expansion in the vicinity of the points of support, the inner packer has no reinforcing. The outer pocket strips, however, are provided with woven fabric reinforcing 30 from the top of each strip to a point just below the bottom of the pockets. This fabric reinforcing serves to prevent the pockets themselves, as well as the portions of the strips that surround the producing tubes, from stretching during inflation of the inner packer. It also serves to prevent the rubber in the vicinity of the pockets from being forced under pressure into the interconnected filling material to thereby interfere with fluid'flow through the pockets. Fabric reinforcing is omitted from the lower portion of the strips, however, in order that the strips may stretch as the inner packer is inflated.

The lower portions of the strips 14 as well as the lower portion of packer 13, it will be noted, are illustrated in Figure 7 to have a somewhat bowed appearance. In other words, the lower portions of these members are shown to be out of contact with the mandrel 12. This structural feature of these members may be readily incorporated into the members as, for example, by using conventional premolding techniques.

it will be noted from Figure 8 that when the packer is in its deflated position the two production pockets cover approximately the full circumference of the tester. When the packer is inflated the production pockets do not change in size since the fabric reinforcing referred to prevents expansion of the pocket strips. It is thus apparent that the formation tester of this invention provides a maximum utilization of formation fluid producing area without limiting the extent to which the inflatable packer can expand. It is readily apparent that if an attempt were made to enlarge the producing pockets in an arrangement where the pockets were integrally mounted on the packer, any substantial enlargement in the producing area would result in a corresponding loss in the ability of the packer to expand to fill the bore hole.

It is to be understood that this invention is not to be limited to the exact description presented which has been by way of example only, but that the invention is to be limited only by the following claims.

What is claimed is:

1. An improved formation tester which comprises an elongated mandrel attachable at its upper end to the lower end of a string of well pipe, an inflatable elastic packer surrounding and extending along said mandrel, a plurality of elongated elastic strip members overlying and extending along said packer, said strips being arranged side-by-side around said packer, reinforcing means in a portion of each said strip member such that said portion is substantially incapable of longitudinal stretching, another portion of each said strip member being unreinforced, means for clamping the upper and lower ends of said packer and of each said strip member against said mandrel, a recessed pocket in the exterior surface of the reinforced portion of each said strip member, interconnected filling material supported within each recessed pocket to render the pocket non-collapsible, a separate non-collapsible flexible conduit enclosed within said reinforced portion of each said strip member and connected at one end to each said pocket and leading exteriorly of said packer to the upper end of said tester.

2. A borehole formation tester including an elongated mandrel attachable at its upper end to the lower end of a string of Well pipe, an elastic sleeve packer surrounding and extending along said mandrel, a plurality of elongated elastic strip members overlying and extending along said packer, said strip members arranged side-by-side around said packer, reinforcing means in a portion of each said strip member such that said portion is substantially incapable of longitudinal stretching, another portion of each said strip member being unreinforced, means for clamping the upper and lower ends of said packer and strip members against said mandrel, a recessed pocket in the exterior surface of the reinforced portion of each said strip member, interconnected filling material filling each said recessed pocket and supported therein, a separate non-collapsible flexible conduit enclosed Within said reinforced portion of each said strip member and connected at one end of each said pocket and extending exteriorly of said packer to the upper end of said tester.

3. An apparatus as defined in claim 2 in which the interconnected packing elements comprise bead chain.

References Cited in the file of this patent UNITED STATES PATENTS 2,143,962 Stone Jan. 17, 1939 2,581,070 Blood Ian. 1, 1952 2,600,173 Sewell et al. June 10, 1952 2,661,803 Ramsey Dec. 8, 1953 

1. AN IMPROVED FORMATION TESTER WHICH COMPRISES AN ELONGATED MANDREL ATTACHABLE AT ITS UPER END TO THE LOWER END OF A STRING OF WELL PIPE, AN INFLATABLE ELASTIC PACKER SURROUNDING AND EXTENDING ALONG SAID MANDREL, A PLURALITY OF ELONGATED ELASTIC STRIP MEMBERS OVERLYING AND EXTENDING ALONG SAID PACKER, SAID STRIPS BEING ARRANGED SIDE-BY-SIDE AROUND SAID PACKER, REINFORCING MEANS IN A PORTION OF EACH SAID STRIP MEMBER SUCH THAT SAID PORTION IS SUBSTANTIALLY INCAPABLE OF LONGITUDINAL STRETCHING, ANOTHER PORTION OF EACH SAID STRIP MEMBER 